1. Advanced VIRGO Experiment
Dal 15 Settembre 2015 al 16 Agosto 2017
F. Frasconi - I.N.F.N. Pisa
Le Onde Gravitazionali e la nascita
dell’Astronomia Multimessaggero
Pisa, October 18th, 2017

2. Sensitivity of 1st Generation ITFs
VIRGO sensitivity: the best one below 100 Hz
Hanford (H1)
F. Frasconi / INFN Pisa

3. Detector Design: AdV Main changes with respect to VIRGO: - larger beam
- heavier mirrors
- higher quality optics
- thermal control of aberrations
- high power laser 200W
- Signal Recycling
Vibration isolation by VIRGO Superattenuators:
- performance compliant with new requirements
- wide experience with commissioning at low frequency (extended detection bandwidth at low frequency).
F. Frasconi / INFN Pisa

4. Mirrors Suspension
The Super-Attenuator (SA) is the mechanical system adopted to isolate the optical components from seismic activities (local disturbances). It is based on the working principle of a multistage pendulum and consists of:
- Inverted Pendulum (IP)
- 6 or 3 Seismic Filters (SF)
- Payload or Last Stage (LS)
F. Frasconi / INFN Pisa

5. The Advanced VIRGO SA IP and Mechanical Filters
A. Basti
New Monolithic Payload with complex geometry
Havier mirrors (about 42 kg) suspended with silica fibers (reduced thermal noise)
F. Frasconi / INFN Pisa
A. Basti

6. New digital electronics
New feedback control electronics based on Multicore DSP technology
Special Thanks to: A. Gennai & D. Passuello
Hardware:
6 ADC + 6 DAC channels;
1 eight-core DSP (up to 60 GFLOPS in double precision);
20 Gbaud RapidIO link on the backplane;
1 Gbps Optical fiber link for DAQ/Global Control.
Software of DSP:
Operative System based on Texas Instruments SYS/BIOS;
Hard real-time control tasks coded using an object oriented language.
F. Frasconi / INFN Pisa

7. The First Detection: GW150914
Hanford (H1)
Livingston (L1)
The false alarm rate bound to 1 event each 203,000 years
False alarm probability < 2*10-7
Statistical significance of the signal > 5.3σ (5.3 Stan. Dev.)
Primary BH mass ≈36 Mꙩ; Secondary BH mass ≈29 Mꙩ;
Final BH mass ≈62 Mꙩ; Event Distance ≈1.3*109 ly.
F. Frasconi / INFN Pisa

8. The signals on aLIGO ITFs
Hanford (H1)
Livingston (L1)
Hanford (H1)
Livingston (L1)
F. Frasconi / INFN Pisa

9. The second GW signal
December 26, 2015 at 3:38:53 UTC a second gravitational wave signal (GW151226) produced by the coalescence of two stellar-mass Black Holes was observed by the two aLIGO interferometers;
The event is very similar to the previous one but with SNR = 13;
Statistical significance of the signal: > 5.3σ.
F. Frasconi / INFN Pisa

10. GW170104
The GW produced by the coalescence of two stellar-mass Black Holes;
The event is very similar to the previous ones with SNR = 13;
False alarm rate < 1 event each years;
Primary BH mass ≈31 Mꙩ;
Secondary BH mass ≈19 Mꙩ;
Final BH mass ≈48 Mꙩ;
Event Distance ≈3*109 ly.
F. Frasconi / INFN Pisa

11. GW170814: Three-Detectors Observation of GW
F. Frasconi / INFN Pisa

12. Localizing GW source
Three detectors observing the same event for a better localization of GW source in the Sky: reduction of about 20 times the selected area w.r.t. that one selected with two ITF;
More precise alert information to be sent to telescopes for further investigation on e.m. field.
F. Frasconi / INFN Pisa

13. GW events on Sky map Hanford (H1) Livingston (L1) Importance of the
detectors Network
F. Frasconi / INFN Pisa

14. Performance comparison for different detectors
Credits: aLIGO
F. Frasconi / INFN Pisa

15. Final Considerations
The upgrade of ground based ITF detectors to a 2nd generation instruments is concluded;
Following the VIRGO experience a big effort has been done implementing complex systems for seismic noise isolation:
- detector bandwidth extended in the low frequency range, below 100 Hz
- improved sensitivity of a factor 10;
A network of 2nd generation detectors will play a crucial role to localize GW source in the sky:
- second observing run (O2) is concluded with 3 detectors (AdV, H1, L1) collecting data at the same time;
- very important and new scientific results obtained;
- data analysis is going on;
The GW astronomy era has just started.
F. Frasconi / INFN Pisa

16. The Father of our SA
Grazie Adalberto !!
F. Frasconi / INFN Pisa

17. Thank you for your attention !!
F. Frasconi / INFN Pisa